(Above: Sen. Sessions tells Obama climate scientist to stick to the facts and quit promoting a political agenda)

White House science czar Dr. John Holdren wasn’t in the mood to be contradicted on whether global warming was causing “extreme weather.” Holdren described climate scientists whose work contradicts the White House’s global warming claims as outside the “scientific mainstream.”

Holdren was asked by Alabama Republican Sen. Jeff Sessions to cite scientific data that supported claims that droughts and other weather events were being made worse by global warming. Sessions then cited contradicting evidence from climate scientists, including former NASA scientist Dr. Roy Spencer and University of Colorado climate scientist Roger Pielke, Jr.

Holdren countered that the likes of Pielke and Spencer “are not representative of the mainstream scientific opinion on this point.”

After Holdren made his remarks about Pielke, he took to Twitter to call the White House science advisor to task.

Testifying today John Holdren @whitehouseostp said my recent Senate testimony is outside the scientific mainstream –>http://t.co/3J2EsiC45d

— Roger Pielke Jr. (@RogerPielkeJr) February 25, 2014

I invite @whitehouseostp to explain where my testimony is incorrect in any way –> http://t.co/3J2EsiC45d

— Roger Pielke Jr. (@RogerPielkeJr) February 25, 2014

Pielke’s research found that “extreme weather” events like hurricanes, tornadoes and wildfires have not increased in frequency or intensity, in contrast to what Democrats and environmentalists argue.

“It is misleading, and just plain incorrect, to claim that disasters associated with hurricanes, tornadoes, floods or droughts have increased on climate timescales either in the United States or globally,” Pielke told the Senate last summer. “It is further incorrect to associate the increasing costs of disasters with the emission of greenhouse gases.”

Holdren may disagree, but Pielke’s research mirrors the findings of the United Nations Intergovernmental Panel on Climate Change (IPCC) — often touted by liberals as the global climate authority. The IPCC also concluded in its most recent climate assessment that there is little evidence to suggest that global warming is causing “extreme weather” events to increase.

The IPCC found that there “is limited evidence of changes in extremes associated with other climate variables since the mid-20th century.” The UN climate bureaucracy also noted that current data shows “no significant observed trends in global tropical cyclone frequency over the past century. … No robust trends in annual numbers of tropical storms, hurricanes and major hurricanes counts have been identified over the past 100 years in the North Atlantic basin.”

“In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale,” the IPCC notes, adding that “that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century due to lack of direct observations, geographical inconsistencies in the trends.”

Dr. Spencer also testified before the Senate last summer that weather has not become more severe in the last century.

“There is little or no observational evidence that severe weather of any type has worsened over the last 30, 50, or 100 years, irrespective of whether any such changes could be blamed on human activities, anyway,” he told the Senate committee last year.

Holdren has been criticized for being outside the “scientific mainstream” as well. He wrote books and essays advocating government-imposed population controls, forced abortions and putting sterilants in the drinking water.

Holdren partnered with fellow scientist Paul Ehrlich on several works advocating for population control, including a 1969 essay entitled “Population and Panaceas: A Technological Perspective” that argued “man’s present technology is inadequate to the task of maintaining the world’s burgeoning billions, even under the most optimistic assumptions.” The essay goes on to argue that technological advancements to increase food supplies would would be fruitless until “the population growth rate drastically reduced.”

Holdren and Ehrlich also coauthored a textbook with one another. One book’s passages argued that coercive population control methods could be constitutional.

“Indeed, it has been concluded that compulsory population-control laws, even including laws requiring compulsory abortion, could be sustained under the existing Constitution if the population crisis became sufficiently severe to endanger the society,” Holdren and Ehrlich wrote. “Few today consider the situation in the United States serious enough to justify compulsion, however.”